Support for event data in proper JSON format

[mguntli]

Problem:
The current plugin requires it's own syntax of how data is published to particle (key=value):
Particle.publish("tvalue", "temperature=20.7");

Proposal:
It's a common approach to group multiple values together in a single event with JSON format in order to limit the number of messages to the particle cloud.

https://www.w3schools.com/js/js_json_objects.asp
JSON objects are surrounded by curly braces {}.
JSON objects are written in key/value pairs.
Keys must be strings, and values must be a valid JSON data type (string, number, object, array, boolean or null).
Keys and values are separated by a colon.
Each key/value pair is separated by a comma.

As an example, an indoor room sensor might transfer the following values:

• temperature [°C]
• humidity [%RH]
• CO2 [ppm]
• VOC [ppb]

The corresponding particle event would look like this (data is limited to 255 byte):
Particle.publish("airquality", "{\"temp\":20.7,\"humid\":45,\"voc\":98,\"co2\":410\"}");

[mguntli]

As a first approach see #21 as a start (only a single value, but with a custom split character for key / value pairs).

[norman-thomas]

Hi @mguntli,
I'm familiar with JSON. This project is work in progress and, tbh, I haven't continued implementing it in a long time because out of connection stability and speed reasons, I switched to using MQTT for my own projects. What I implemented you can check here: https://github.com/norman-thomas/omni-sense. There I already use JSON as well as single values.
If you would like to have JSON support in this project and have a bit of time, feel free to implement it and I will merge it. I would like to implement it, but sadly am a bit short on time these days.

Thanks for your pull request #21 , I already merged it and hope it helps you for now.